UsbCamera Class

Package: GHIElectronics.Endpoint.Devices.Camera
Namespace: GHIElectronics.Endpoint.Devices.Camera

A webcam: any USB Video Class camera. Pictures come as JPEG files, whether the camera sends MJPEG or raw YUYV pictures.

public sealed class UsbCamera : IDisposable

Remarks

Open it with the DeviceName of a Webcam from UsbHostController ("/dev/video0"). The first picture waits until the camera's automatic exposure has settled (about a second); while pictures are taken the camera keeps running, so the next ones come at once. At first the size is 640x480. The events come on the camera's own thread. A camera stays alive until it is disposed.

Nested Types

Type	Kind	Summary
UsbCamera.DisconnectedEventHandler	Delegate	The handler of Disconnected
UsbCamera.FrameReceivedEventHandler	Delegate	The handler of FrameReceived

Constructors

UsbCamera(string deviceName)

public UsbCamera(string deviceName)

Opens the camera that UsbHostController reported ("/dev/video0").

Properties

Connected

public bool Connected { get; }

true while the camera is physically present on the USB bus.

Returns bool

DeviceName

public string DeviceName { get; }

What the camera was opened with: "/dev/video0"

Returns string

FrameRate

public int FrameRate { get; }

The frame rate in use (frames per second)

Returns int

Height

public int Height { get; }

The picture height in use

Returns int

IsStreaming

public bool IsStreaming { get; }

Whether StartStreaming is on

Returns bool

JpegQuality

public int JpegQuality { get; set; }

The JPEG quality (1 to 100) of pictures the library makes from raw YUYV pictures. Defaults to 85.

Returns int

Name

public string Name { get; }

The camera's name ("USB 2.0 Camera: USB Camera")

Returns string

PixelFormat

public CameraPixelFormat PixelFormat { get; }

What the camera sends for the size in use

Returns CameraPixelFormat

SupportedControls

public IReadOnlyList<CameraControl> SupportedControls { get; }

The controls this camera has

Returns IReadOnlyList<CameraControl>

SupportedFormats

public IReadOnlyList<CameraFormat> SupportedFormats { get; }

The sizes the camera has, with what it sends for each

Returns IReadOnlyList<CameraFormat>

Width

public int Width { get; }

The picture width in use

Returns int

Methods

Capture(int timeout)

public byte[] Capture(int timeout)

Takes a picture: a JPEG.

Parameter	Type	Description
timeout	int	How long to wait for the camera, in milliseconds (the first picture also waits for the exposure).

Returns byte[]

Capture(string path)

public void Capture(string path)

Takes a picture and saves it as a JPEG file.

Dispose()

public void Dispose()

Stops the camera (a frame being delivered finishes first) and closes it

GetControl(CameraControl control)

public CameraControlValue GetControl(CameraControl control)

A control's range and value.

Returns CameraControlValue

SetControl(CameraControl control, int value)

public void SetControl(CameraControl control, int value)

Sets a control, in the camera's own units (GetControl gives its range).

SetResolution(int width, int height, int frameRate)

public void SetResolution(int width, int height, int frameRate)

Uses a size the camera has (MJPEG if the camera has it at that size, else YUYV).

Parameter	Type	Description
width	int	The width, one of SupportedFormats'.
height	int	The height.
frameRate	int	Frames per second; 0: the camera's highest for that size.

SetResolution(CameraFormat format, int frameRate)

public void SetResolution(CameraFormat format, int frameRate)

Uses one of SupportedFormats, as it is (YUYV too).

StartStreaming()

public void StartStreaming()

Starts streaming: every frame comes as a JPEG in FrameReceived.

StopStreaming()

public void StopStreaming()

Stops streaming; UsbCamera.FrameReceived no longer fires. A frame being delivered finishes first.

Events

Disconnected

public event DisconnectedEventHandler Disconnected

The camera was unplugged

FrameReceived

public event FrameReceivedEventHandler FrameReceived

A frame while streaming (StartStreaming)